My fish began exibiting the following almost immediately after a water change:

1. his sides seem to be bloated
2. very sluggish, lays on bottom a lot
3. not eating; Note: he started new food about a day before i changed the water
4. long white thread-like thing protruding from just behind where his gills are on his belly
5. silver spot under his gills

When you did the water change, was it done with a similar water temperature he had before? He could be lethargic if there was an abrupt temperature change. Also, sometimes they can get bloated easily after you feed them (what kind of food is it...flakes I've heard can cause bloating if not soaked before the fish ingests them) This bloating can cause pressure on the swim bladder, he could be experience swim bladder disease. Is he having trouble stay balanced when he swims? Does he seem to try to swim up but then sinks straight to the bottom?

Could you send a picture of the long thread like thing from his gills? It may help better understand his condition.

That's a very good photo nice and clear, um well it looks like it could be pale colored feces atm sometimes it'll take a while for it to pass like hours or a day or do. I think this because of the ball at the end. Sometimes if mine have a really full belly they will take longer to pass their feces.

But if it does not go away or it moves and wriggles it could be an internal parasite itself...OR if the pooh remains white in color it could mean internal parasites could be a problem. I don't think it is atm UNLESS you continue seeing white pooh. That may describe lack of appetite, but again I don't think you need to worry about it being that just yet.

The silver spot under his gills (if you mean on his chin and belly) seems to be normal coloring, my green betta has that as well, but his gets darker once and awhile and light again. I remember thinking it was strange his chin looked silver one day.

Okay so the water change probably didn't do it. Um some important questions what is the temp? is it filtered? any tank mates? what is his food? ammonia level?